The Lights Of The World

Scientists at the Goddard Space Flight Center in Maryland and Yale University in Connecticut used satellite imagery to track light patterns in 1,200 cities over two and a half years. They found that increased light correlated perfectly with the holiday seasons for Ramadan in the Middle East, as well as Christmas and New Year’s Eve worldwide. They also saw variations in how cities and neighborhoods within those cities celebrate these holidays, the team announced this week at the American Geophysical Union’s annual meeting in San Francisco.

“What’s happening during the holidays is our patterns are changing,” says Miguel Román, a physical scientist at NASA Goddard. In the West, we’re staying up late drinking eggnog and going home from work early. “Those changes in behavior are changes in the locations of demand for energy services.” Understanding such seasonal shifts might ultimately tell us what’s driving carbon emissions at a local level.

[The researchers] examined three years, from 2012 through 2014, and saw a marked lighting increase in Cairo:

This time, of course, the lighting isn’t Christmas lights. Rather, it’s people changing their schedules due to the religious holiday. “It’s a change in the timing of human activity, because people are fasting from dawn to dust,” says Yale’s Eleanor Stokes. “So activity, commerce, heating, family gatherings are all being pushed later into the night.”

The Cairo picture shows something else interesting as well, notes Stokes — economic differences. The researchers found that in poorer areas, people were still celebrating Ramadan but were not using more energy at night, presumably instead choosing to conserve and save money.